The US and European Union today renewed calls for the immediate release of high profile dissident Liu Xiaobo, as a Chinese court upheld his 11-year-sentence.

He was convicted for inciting the subversion of state power after co-authoring Charter 08, a call for greater political freedoms. Although the vaguely-worded offence carries a maximum term of up to 15 years, the writer's sentence was one of the longest handed out in recent years on the charge.

But a reduction would have been remarkable in such a high-profile political case and his wife said she had expected the decision. She added that Liu shouted out his innocence after hearing the court's statement.

Diplomats were not allowed into the brief hearing but gathered outside the Beijing court as US and EU spokesmen criticised the decision.

The US ambassador, Jon Huntsman, said that Liu should not have been sentenced in the first place and should be released immediately, in a statement read by an American diplomat.

"Persecution of individuals for the peaceful expression of political views is inconsistent with internationally recognised norms of human rights," he added.

Simon Sharpe, the spokesman for the EU delegation in China, said: "The European Union believes that the verdict against Liu Xiaobo for his role as author of Charter 08 and for publishing articles concerning human rights on the internet is entirely incompatible with his right to freedom of expression.

"The EU calls on the Chinese government unconditionally to release Mr Liu and to end the harassment and detention of other signatories of Charter 08."

Campaigners fear the heavy sentence is indicative of an increasingly punitive approach to human rights activism and political dissent in China.

The author's wife, Liu Xia, said: "I was already mentally prepared for this result. I know the chance to change it in future is very slight.

"The court session lasted less than 10 minutes – they just read the verdict. At the end, Xiaobo shouted: 'I am innocent'."

She said she saw him briefly at a detention house afterwards, adding: "At the end of the meeting I asked to hug him and it was allowed. I felt he was thinner, although he always says his health is good. Of course, he won't tell me if it isn't."

Police detained Liu, 54, the day before the online publication of Charter 08, which was signed by more than 300 people. Thousands more later added their names.

But censors swiftly erased it from websites and many of the original signatories were harassed, threatened or detained.

The former university professor was held for almost a year without charge and convicted on Christmas Day last year. Liu previously spent 20 months in jail after joining the Tiananmen Square pro-reform protests in 1989 and was sent to a re-education through labour camp in the 1990s.

"By upholding the verdict [today] the court missed an opportunity to right the wrong. His harsh sentence is a stark reminder to the Chinese people and the world that there is still no freedom of expression or independent judiciary in China," said Roseann Rife, Asia-Pacific deputy director at Amnesty International.

Asked about the case at a regular news briefing, Foreign Ministry spokesman Ma Zhaoxu said: "China has no 'dissidents'.

"We only act in accordance with the law. There is only the difference between criminals and those who are not criminals."